NZTA's Otago-Southland Highways Manager, Ian Duncan said the wintry storm that swept through both regions had now been followed by clearing, cold weather, making black ice a real danger. This form of ice was especially treacherous because it could not be seen.

"Winter roads demand winter driving and motorists can keep themselves safe by lowering their speeds, increasing their following distances, and taking extra care when cornering."

Mr Duncan said icy conditions meant trips took longer and motorists should allow more time and consider departing later in the morning to allow ice to thaw, or leave earlier in the afternoon before ice formed.